First, all concrete cracks. We as installers try to place control joints in proper places in your slabs so that when concrete cracks it’s in the areas it is supposed to. Control joints need to be installed the same day or the next day at the latest. The joints should also be divided evenly throughout the slab, and must be a 1/4 the thickness of the slab.

Second, concrete installed on poorly compacted fill or bad fill tends to crack faster and in other areas aside from the control joints.